Dimethylsulphoxide water

Cell (D) has been used several times to determine the solvent transference number A of the sparingly soluble salt Ag2S04 in the binary solvent mixtures acetonitrile-water l, dimethylsulphoxide-water and dimethylsulphoxide-methanol In Fig. 3 the solvent transference number of Ag2S04 is plotted versus Xdmso =... 

Bilirubin in serum Hypersil ODS Acetonitrile /dimethylsulphoxide /water (40 40 20) UV 450 nm 141... 

In view of the diversity of medium effects between water and dimethylsulphoxide, we must expect any acidity function that is anchored to the pH scale in water to apply only to acids with very similar structures. Dolman and Stewart have reported values of the H acidity function in dimethylsulphoxide-water mixtures based on 24 substituted aniline and diphenylamine indicators. Dimethylsulphoxide containing 0.4 mol per cent water has a H value of 26.2. 

DMSO - Dimethylsulphoxide is a very common solvent with a freezing point of 20 degrees. When you buy this stuff it will be crystallised in the bottle. To melt, all you need to do is place the bottle in a bowl of hot water for 30 minutes - simple. If you re lucky enough to live somewhere warm it may already be liquid, where I live, no chance. When you open the bottle you will notice that this stuff smells a bit farty, don t worry too much, it doesn t get that bad. 500ml straight into the reaction flask and start the stirrer. 

For Yiv < Ypv the opposite behavior pattern is predicted, namely AFads decreases with increasing ysv, thus stronger adsorption occurs. Indeed, adsorption of IgM from the dimethylsulphoxide solutions in water (y,v = 63.2 67.2 69.1) increases with increasing substrate surface tension (ysv)-... 

Most protic solvents have both protogenic and protophilic character, i.e. they can split off as well as bind protons. They are called, therefore, amphiprotic. These include water, alcohols, acids (especially carboxylic), ammonia, dimethylsulphoxide and acetonitrile. Solvents that are protogenic and have weak or practically negligible protophilic character include acid solvents, such as sulphuric acid, hydrogen fluoride, hydrogen cyanide, and formic acid. 

TLC has been applied for the purity control of the newly synthetized o,o -dihydrox-yazo dyes and their chromium complexes. The structures of 7-hydroxy-o,o -dihydrox-yazo dyes and their chromium complexes are listed in Fig. 3.14. TLC purity check of o,o -dihydroxyazo dyes and their chromium complexes was performed on silica layers using 5 per cent water/ethanol and 5 per cent water-dimethylsulphoxide as the mobile phase, respectively. The formula and Rp values of 7-hydroxy-o//-dihydroxyazo dyes and their chromium complexes are compiled in Table 3.10. The retention values indicated that the TLC technique applied is suitable for the purity control of the these new dye compounds [92],... 

The use of ISEs in non-aqueous media(for a survey see [125,128]) is limited to electrodes with solid or glassy membranes. Even here there are further limitations connected with membrane material dissolution as a result of complexation by the solvent and damage to the membrane matrix or to the cement between the membrane and the electrode body. Silver halide electrodes have been used in methanol, ethanol, n-propanol, /so-propanol and other aliphatic alcohols, dimethylformamide, acetic acid and mixtures with water [40, 81, 121, 128]. The slope of the ISE potential dependence on the logarithm of the activity decreases with decreasing dielectric constant of the medium. With the fluoride ISE, the theoretical slope was found in ethanol-water mixtures [95] and in dimethylsulphoxide [23], and with PbS ISE in alcohols, their mixtures with water, dioxan and dimethylsulphoxide [134]. The standard Gibbs energies for the transfer of ions from water into these media were also determined [27, 30] using ISEs in non-aqueous media. 

The toxicity of silatranes is considerably influenced by the nature of the solvent. Thus, the toxicity of silatrane solutions in dimethylsulphoxide is considerably higher than in water and tween. On skin application 1-arylsilatranes in DMSO solutions are fairly toxic as well, but not toxic in the solid state and in aqueous solutions. 

The effect of lithium perchlorate on the rate of reaction (44) (R = Me, X = Br) in solvent dimethylsulphoxide is unfortunately within experimental error, so that a calculation on the above lines would be meaningless. Since, however, mechanism SE2(open) is in force when dioxan(4) water(l), of e25 = 10.5, is the solvent, it would not be unreasonable if a similar mechanism applied also to reaction (44) (R = Me, X = Br) when dimethylsulphoxide, of 25 = 46.5, is the solvent. 

The one-phase liquid system is more frequently encountered since many organic reactions are carried out in solution. Direct fractional distillation may separate the product, if it is a liquid, from the solvent and other liquid reagents, or concentration or cooling may lead to direct crystallisation of the product if this is a solid. However, it is often more appropriate, whether the required product is a liquid or solid, to subject the solution to the acid/base extraction procedure outlined above and considered in detail on p. 162. This acid/base extraction procedure can be done directly if the product is in solution in a water-immiscible solvent. A knowledge of the acid-base nature of the product and of its water solubility is necessary to ensure that the appropriate fraction is retained for product recovery. In those cases where the reaction solvent is water miscible (e.g. methanol, ethanol, dimethylsulphoxide, etc.) it is necessary to remove all or most of the solvent by distillation and to dissolve the residue in an excess of a water-immiscible solvent before commencing the extraction procedure. The removal of solvent from fractions obtained by these extraction procedures is these days readily effected by the use of a rotary evaporator (p. 185) and this obviates the tedium of removal of large volumes of solvent by conventional distillation. 

A 50% w/v solution of sodium hydroxide in water (12.5 ml, 0.32 mol) was added to a mechanically stirred suspension of diphenylacetonitrile (15.0 g,0.08 mol) and dibenzo-18-crown-6 (0.5 g, cat.) in dimethylsulphoxide (12.5 ml). The color rapidly deepened to an orange/brown. R-(-)-l-Dimethylamino-2-chloropropane (30.0 g, 0.095 mol) was added in portions over 30 min, this caused the temperature to rise to 30°C. After the addition was complete the mixture was warmed to 45°-50°C (water bath) and stirred for a further hour. The reaction mixture was then allowed to cool to room temperature and was poured into ice/water (250 ml) and extracted with ethyl acetate (3 times 150 ml). The combined extracts were dried (MgS04) and filtered and evaporated down to -100 ml. The product was extracted into IN HCI (100 ml+50 ml) and this was back washed with ethyl acetate. The aqueous was basified with 2 M sodium hydroxide and extracted into ethyl acetate (3 times 100 ml). The extracts were washed with brine (70 ml), dried (MgS04), and evaporated down to a yellow oil. This was chilled and triturated with cold hexane (50 ml) to give a white solid which was collected by filtration and washed thoroughly with a further portion of cold hexane (100 ml). 14.65 g (33%) of S-(+)-2,2-diphenyl-4-dimethylaminopentanenitrile were obtained, melting point 100°-101°C (recrystallised from hexane). 

Kabanov et al. have studied the radical polymerization of acrylic acid in aqueous solutions [61] (see Chap. 4, Sect. 1.4). A crystaline, syndiotactic polymer was formed at pH 10.2-10.8. The kinetics of the photosensitized polymerization of acrylic acid was studied by Galperina et. al. [62], They observed a strong solvent dependence for the rate constant of propagation. At 293 K, kp[mol-1 dm3 s-1] = 22 500 in water, 4 200 in formamide, and 500 in dimethylsulphoxide. 

An outstanding exception is the solvation of ions in dimethylsulphoxide (DMSO)-water mixtures. While in dimethylsulphoxide AG (Ag ) related to water is negative, in highly aqueous DMSO mixtures Ag is preferentially hydrated The change of preferential solvation of an ion with solvent composition has also been noticed for other ions This behavior can be attributed to the stabilization ... 

A reaction with mechanism (99) should show general base catalysis but under some conditions this catalysis is difficult to detect and the rate may be dominated by hydroxide ion catalysis. However, recent work has now been carried out on the detritiation of chloroform in which general base catalysis by amines was observed [171(a)]. In the work with chloroform in which general base catalysis was not detected [114], since it was not possible to obtain a Bronsted exponent by measuring catalytic coefficients for a series of bases, an alternative procedure first suggested by Bell and Cox [172] was used. The rate of detritiation of chloroform was measured in a mixed solvent of water with varying amounts of dimethylsulphoxide and a constant concentration of hydroxide ion. As discussed briefly in Sect. 4.4 an acidity function (H ) has been determined for these solvent... 

Delpuech and co-workers [190] have begun a comparative study of proton transfer behaviour for amines in water and dimethylsulphoxide using NMR methods. Proton transfer rates for amines in aqueous solution were originally studied using NMR [10, 191]. It is found [190] that rate coefficients for reaction (108)... 

The radio-HPLC equipment considered of 2 Waters model 6000 A pumps, a Waters 660 solvent programmer, a Waters U6K injector, a Varian Varichrom UV-VIS spectrophotometric detector, a FMI LB 5031 scintillation cocktail pump, a Berthold Radioactivity Monitor LB 504 fitted out with an 800-pl flow-cell and a Spectra-Physics SP 4100 computing integrator. Dried extracts were dissolved in minimal amounts of dimethylsulphoxide for injection. 

Formulations containing an absorption promoting substance, such as propylene glycol or sodium lauryl sulphate, may increase the permeability of the stratum comeum to water-soluble drugs. Propylene glycol is a commonly used vehicle in topical corticosteroid preparations for veterinary use. Various aprotic solvents, which include dimethylacetamide, dimethylformamide, dimethylsulphoxide, tetrahydrofurfuryl alcohol, and 2-pyrrolidone, serve as penetration enhancers of polar drugs (Barry, 1983). Dimethylsulphoxide... 

Dimethylsulphoxide is a universal solvent but can cause itching erythema and uticaria when applied to skin. However, it has been used medicinally in bladder instillations (at 50% in water) for interstitial cystitis, and is a vehicle for idoxuridine for herpes infections (though is of little value). Together with acetone, DMSO is a class 3 solvent under the FDA guidance, not known as a human health hazard at levels normally expected in pharmaceuticals and which can thus be limited by appropriate GMP practices. 

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